The development of droplet-based microfluidic devices is driven by the need to screen large and varied libraries of molecules for interactions with populations of cells, enzymes, nucleic acids, and other biomolecular materials. Efficient screening requires an instrument to encapsulate individual elements of the molecular library with single or multiple cells, particles, or other biomolecules, perform an assay on the contents, perhaps through the addition of one or more reagents, and then, finally, to identify and selectively collect only the microreactors containing promising molecules. This requires a processing rate of 10A3 elements per second to sort through the smallest libraries in a reasonable time while rates on the order 10A5 per second are desirable for larger libraries. These rates are feasible by combining our proprietary microfluidic nanoreactor technology with high speed electric field based control and sorting. Upon successful completion of this integration, RainDance Technologies, Inc. will have developed an enabling technology capable of rapidly and economically screening enormous molecular libraries in timescale measured in hours instead of weeks. [unreadable] [unreadable] [unreadable]